Adaptor for operating d.-c. timing device on a.-c. supply line



Nov. 28, 1961 A. c. REYNOLDS, JR 3,011,078

ADAPTOR FOR OPERATING D.C. TIMING DEVICE ON A.C. SUPPLY LINE Filed July10, 1957 CUEEECf/O V can CLOCK 6''. a an;

INVENTOR W United States Patent 3 011 078 ADAPTOR non oi nnhrnvo D.-C.TIMING A DEVICE N A.-C. SUPPLY LINE ntgrgzlgigigi lteynglds, Jr.,Waterbury, Conn., assignor lme pomfion of Delawatiiporatlon, New York,N.Y., a cor- Filed July 10, 1957, Ser. No. 670,954 16 Claims. (Cl.307-140) The present invention relates primarily to an electricalcontrol system for operating step-by-step D.-C. timing devices on acommon A.-C. power system. mfgteiytgglclk rrlifzsitensecond ary clocksystem employs a t t i a plurality of secondary clocks, with each ol'the secondaries being automatically corrected at regular intervals toinsure that they remain in synchrorciizigiksvgirtii S'lgibmaLSiSIbgogvcntionallLthe secondary by dvanc A y-siep cvices, that 13, theyoperate t mg discrete increments usually minute by minute, 1n responseto impulses received over a special D.-C. line. At the end of apredetermined interval, usually every hour, the master clock initiates acorrecting signal which is received by the secondary clocks and operatesto bring the latter into synchronism with the master.

A particular and commonly utilized operating and correctmg device for asecondary clock in such a system is known as an autoset mechanism and isfully disclosed and described in US. Patent No. 2,332,828, issuedOctober 26, 1943. For purposes of the present disclosure it will besufficient to observe than an autoset mechanism of this type requires arapid series or" D.-C. corrective impulses, having a polarity which isthe reverse of the normal minute impulses for resetting purposes, suchimpulses being supplied to the autoset mechanism from the master clockover a definite time interval toward the end of each hour. 0 Briefly,the autoset mechanism accomplishes its correctmg function by locking itsadvancing solenoid if a current impulse of reverse polarity is receivedand the secondary clock is on time. If the clock is slow when the masterclock initiates the rapidcorrective impulse series, the locking means isdisabled and the rapid impulses quickly advance the clock setting untilthe clock has been corrected and the locking means rendered eiiective tolock the solenoid against the remaining corrective impulses in theseries. With the next minute impulse of normal polarity, the clockadvances normally.

Thus it can be seen that the autoset mechanism of a secondary clock mustbe provided both with regular minute, or other fixed interval, impulsesof D.-C. current for normally advancing the clock setting, and with aseries of rapid corrective impulses of reverse polarity initiated, andunder the control of, the master clock for keeping the secondary insynchronism with the master. The advantages of reliable and precisesynchronization provided by the autoset mechanism have not beenconventionally available except at the cost of running the special D.C.control lines mentioned above.

Accordingly, it is an object of this invention to provide a noveladaptor permitting an autoset equipped, step by-step timing device tooperate on a common A.-C. power supply line in synchronism with a masterclock. More specifically, it is an object to provide such a device whichwill normally produce a D.-C. impulse at regular predeterminedintervals, and will also produce, upon receiving an initiating signal, arapid series of D.-C. impulses of reverse polarity over a predeterminedtime interval before resuming normal operation.

It is also an object to provide an adaptor of the type described above,which can be actuated to produce a rapid predetermined series of reversepolarity D.-C. im-

3,011,078 Patented Nov. 28, 1961 pulses when desired withoutinterrupting or varying the regular output of D.-C. impulses of normalpolarity at predetermined time intervals.

' It is another object to provide an adaptor of the type characterizedabove which'has few parts and elements so as to permit compactconstruction for use within the narrow space limitations of clockhousings. It is a related object to provide an adaptor of this typethatis quick and convenient to install. 1 it is moreover an object toprovide an adaptor of the above type which permits D.-C. operatedmaster-secondary clock systems to be extended or converted to A.-C.operation without sacrificing existing equipment.

It is a further object toprovide an adaptor of the type characterizedabove that is reliable and accurate, and which is of simple andstraight-forward design so as to retain its reliability and accuracythroughout a long service life. It is a collateral object to provide anadaptor of this type that uses conventional motors and cams, andtherefore is economical to manufacture and trouble-free to operate.

In one of its aspects it is an object of the invention to provide asignal controlled, motor driven device which cannot be unintentionallyactuated by spurious,transient signals, even though a number of suchsignals are successively received. With more particularity, it is anobject toprovide an adaptor as described above having a simple andreliable device preventing unintentional actuation by transient,spurious signals. 7

Other objects and advantages of the invention will be come apparent uponreading the attached detailed description and upon reference to thedrawings in which:

FIGURE 1 is a schematic wiring diagram showing the adaptor of thepresent invention connected to operate a step-by-step device. i.

FIG. 2 is an enlarged fragmentary perspective view of the time delaydevice shown somewhat schematically in FIG. 1.

FIG. 3 is a block diagram of a typical control station.

While the invention will be described in connection with a preferredembodiment, it will be understood that I do not intend to limit theinvention to that embodiment. On the contrary, I intend to cover allalterations, modifications and equivalents, as may be included withinthe spirit and scope of the invention as defined by the appended claims.

Turning first toFIG. 1, there is schematically shown an adaptor 10installed between a step-by-step D.-C. clock or timing device ll havingan actuating solenoid 12, and terminals 13 and 14 intended to beconnected to a conventional A.-C. power system. In the timing device 11,the solenoid 12 forms a part of an autoset mechanism of the typedisclosed in the US. Patent 2,332,828 referred to above and is providedwith two terminals 15 and 16. For present purposes it will be sufficientto note that when the solenoid 12 is energized by a D.-C. currentimpulse making the terminal 15 positive and the opposite terminal 16negative, normally once during each minute, the autoset mechanism iseffective to advance the timing device 11 one step forwardly. And asmore fully spelled out in the above patent, when the solenoid 12 isintermittently'energized by a rapid series of D.-C. current impulses ofre versed polarity, with terminal 15 negative and the terminal 16positive, as normally occurs near the end of each hour, the autosetmechanism tends to correct the setting of the timing device 11 so thatthe latter remains in syn chronism with a master clock.

Prior to discussing the present mechanism it will be helpful to have inmind the complete system to which the invention is applicable. Aplurality of secondary clocks 11 are used, each capable of responding toD.-C. im-

pulses which are generated in an adaptor of the type to be described insynchronism with the cycles in the A.-C. supply line. At a centralcontrol station (FIG. 3) there is provided a master clock M and a highfrequency carrier transmitter T suitably coupled to the line. At apredetermined instant toward the end of each hour, e.g., at the 59thminute, the master clock closes contacts for the sending out of asynchronizing signal by the transmitter to all of the clocks on theline, serving to bring them to an accurate reference position, forexample the hour position, thereby taking care of slowness due to anypower interruptions which may have occurred during the preceding hour.The carrier signal is received at each clock or timer location by areceiver -R which is tuned to the transmitter. Obviously other carriersignals may be applied to the supply line for the control of otherremote equipment without affecting the clocks, provided that differentcarrier frequencies are used. In lieu of the carrier signal receiver R,it is alternatively contemplated that a signal carrying conductor may beextended from the master clock to the adaptor so that the master clockmay transmit its correcting signal through the conductor directly to theadaptor without converting the correcting impulse to a carrier signal.

To provide a source of D.-C. current the adaptor 10 preferably includesa full-wave rectifier 17 of the conventional type which is connected,through the terminals 13, 14 to the A.-C. power system It will beunderstood that a storage battery or other source of D.-C. current canbe utilized in lieu of the rectifier 17 without varying the operation ofthe adaptor 10'.

In accordance with the present invention, the adaptor 10 includes afirst motor adapted to normally transmit intermittent D.-C. impulses,and a second motor adapted to be energized for a single cycle by themaster clock and which is effective to interrupt operation of the firstmotor, reverse the polarity of the D.-C. current source, and transmit arapid series of D.-C. impulses of reversed polarity until the end of itscycle, whereupon the first motor is reenergized and normal operationresumed. In the illustrated embodiment, the adaptor 10 includes a firstself-starting, synchronius motor 20' connected to the A.-C. power systemat terminals 13, 14 through normally closed contacts 21 forming a partof a three-pole, doublethrow, switch 25, to which later detailedreference will be made.

In order to transmit a regularly intermittent D.-C. impulse to theautoset solenoid 12, the motor 2i) drives a minute impulse cam 26through a gear box 27 and a camshaft 28. The cam 26 has a drop offportion 29 which is effective to intermittently close the contacts 30 asthe cam 26 is rotated. Closing the contacts 30 completes a D.-C. circuitthrough the contact sets 31, 32 of the switch 25 and energizes theautoset solenoid 12, the solenoid terminal being made positive and theterminal 16 being made negative. In the preferred embodiment the minuteimpulse motor drives the camshaft 28 at 1 rpm. and there is a singledrop off portion 29 formed on the cam 26. Thus, exactly once eachminute, for a period of approximatelytwo seconds, the contacts 30 areclosed and the solenoid 12 energized for the purpose of advancing thestep-by-step timing device 11.

In order to respond to the correcting signals regularly transmitted bythe master clock and to produce the required correcting impulses ofreverse polarity for the solenoid 12, the adaptor 10' is provided with asecond self-starting synchronous motor 35. To energize the motor 35, thecarrier signal receiver R is connected to a normal- 1y open relay 66which closes the contacts 67 when a correcting signal is received fromthe master clock and thus connects .the motor 35 to the A.-C. powersystem through the terminals 13, 14.

The signal transmitted by the master clock and received by the carriersignal receiver R is only of a few seconds duration, and therefore, toinsure that the motor 35 remains energized through a complete correctingcycle, a seal-in circuit is provided for the motor. To understand theseal-in circuit, attention must be first paid to the operation of theseal-in switch 25 referred to above. The switch 25 is operated by aseal-in cam 36 that is fixed to a rotatable camshaft 3'7 driven by themotor 35 through a gear box 38. A time delay device 4!) is interposed inthe driving train and later detailed reference will be made to thisstructure. It will be sufficient at this point to note that as soon asthe motor 35 remains energized for a brief period, the time delay device40 will transmit the rotation of the motor to the cam 36, whereupon theswitch 25 is operated and remains operated throughout its engagementwith the outer peripheral dwell portion 41 of the cam 36.

Returning to the seal-in circuit for the motor 35, operation of theswitch 25 closes the contacts 42 and completes a circuit to maintain themotor 35 energized so long as the switch 25 remains operated. In thepreferred embodiment, the motor 35 drives the cam 36 at 1 rpm. and thedwell portion 41 extends substantially entirely around the cam 36, sothat only in one position of the cam is the switch 25 not operated. Inthis way, once the motor 35 has been energized and the switch 25operated to close the contacts 42, the motor 35 remains energized for aperiod of one minute as the seal-in cam 36 makes one completerevolution.

When the motor 35 is energized and sealed-in for one complete revolutioncomprising a single cycle, the operation of the minute impulse motor 26is interrupted for the full cycle interval, since the operation of theseal-in switch 25 will open the contacts 21 and deenergize the motor 26.The operation of the switch 25 is also effective to reverse the polarityof the source of D.-C. current available to energize the autosetsolenoid 12. This is accomplished by opening the contact sets 31, 32 andclosing the contact sets 43, 44 when the switch 25 is operated.

To produce the rapid series of reverse polarity current impulses for thesolenoid 12, a second cam 45 is mounted on the'camshaft 37 so as to bedriven by the motor 35. The cam 45 has a plurality of switch actuatingrise portions 46 formed about its periphery which are effective torepeatedly and intermitte 'tly close contacts 47 and complete a circuitenergizing the autoset solenoid 12 with current impulses of reversedpolarity, that is, each impulse making the terminal 15 negative andterminal 16 positive. In the preferred embodiment, the cam. 45 is formedwith twenty evenly spaced switch actuating rises 46 and thus the cam,making one complete revolution during the one minute cycle, willtransmit twenty rapid corrective impulses to the autoset solenoid 12,spacing them one every three seconds.

It will be appreciated that after the motor 35 completes one cycle ofoperation, the operation of the sealin switch 25 will be interrupted,thus opening the contacts 42 to deenergize the motor 35 and closing thecontacts 21 to energize the motor 29. When the switch 25 is no longeroperated, the contact sets 31, 32 are again closed to reestablish thecircuit through the contacts 36 and thus permit the minute impulse cam26 to resume its normal operation of transmitting one current impulse ofnormal polarity to the autoset solenoid 12 each minute.

So that the adaptor may be accurately phased to resume generation of theregular timing impulses following the completion of the rapid correctiveimpulse cycle and the return of control to the motor 20, a fourth switchactuating cam 50 is fixed to the camshaft 28 to be driven by the motor20. The cam 50 has a dwell portion 51 extending substantiallycontinuously about the periphery of the cam, and the dwell portion 51 iseffective to close the contacts 52 which complete a circuit, by-passingthe contacts 21, energizing the motor 20. The cams 50 and 26 areproperly phased by being J relatively angularly fixed to the camshaft 28so that the contacts 52 are open only when the dwell portion 29 of thecam 26 is poised to close the contacts 30. Thus, it can be seen that nomatter when a signal is received from the master clock causing the motor35 to be energized, the switch to be operated, and the contacts 21 to beopened, the motor 20 will continue to rotate, although its ener izingcircuit through contacts 21 has been broken, since the cam 50 willmaintain the contacts 52 closed. The motor 20 will continue to rotatethe camshaft 28 until the cam 50 has reached the angular position inwhich the contacts 52 open and the dwell portion 29 of the cam 26 ispoised to close the contacts 3t The significance of the cam 5t can beappreciated when it is understood that the master clock initiates thecyclic operation of the motor 35 at a regular predetermined time,preferably at exactly 59 minutes past the hour. Since the singlerevolution cycle of the cams 36, 45 operated by the motor 35, lastsexactly one minute, the correct time when operation of the switch 2-5 isceased and control of the autoset solenoid is returned to the minuteimpulse cam 26, is exactly 60 minutes past the hour. Thus, the device 11must be immediately ad- "Vanced another one minute interval in order tomaintain it in synchronism with the master clock. By utilizing the cam50 to position the cam 26 so that the contacts are closed immediatelyupon the reenergization of the motor 20, the required impulse of normalpolarity is transmitted at the proper time to the solenoid 12 and thedevice 11 is advanced in exact synchronisrn with the master clock'Moreover, by angularly phasing the cams 26 and 50 so that the motor 26is stopped, by the cam 50 opening the contacts 52, just before thecontacts 3% are closed, rather than at the instant when they do close, acomplete, normal, operating cycle of the contacts 30 by the cam 26 isassured when the motor Ztl is reenergized. Thus, the contacts 39 willremain closed for their full normal interval to energize the solenoid 12and advance the device 11. If the contacts 30 were allowed to remainclosed during the interruption in operation of the motor 20, the timeneeded to break the contacts when the motor 2t? is again energized wouldbe less than the full normal interval during which the contacts areclosed, and the shorter periodmight well prevent normal operation of theautoset mechanism.

Further in accordance with the invention, the motor is provided with atime delay device 49 so that the motor '35 will not be unintentionallycycled by spurious, transient signals received at the terminals 13, 14even though several such signals are successively received by thecarrier signal receiver R. it will be understood that spurious, stray,high frequency signals are often induced in an A.-C. power system byvarious electrical devices, these signals being a form of static andpossessing frequency components Within a range which will cause aresponse from the carrier signal receiver R. These signal-s, however,are of short duration, and therefore a spurious, transient signalreceived by the carrier signal receiver R will cause only a momentaryenergization of the relay 66 which only briefly closes the contacts 67.By providing the motor 35 with a time delay device, the brief closingsof the contacts 67 caused by spurious, transient signals are ofinsuflicient duration to seal-in the motor 35 and thus will not initiatea false operating cycle.

In the present embodiment, the time delay device comprises a springbiased, lost-motion, driving connection between the output shaft of themotor 35 and the camshaft 37, which is arranged so that when the motorstarts rotating, it must first overcome the spring force and take up thelost-motion before the camshaft 37 is rotated. To provide thelost-motion connection, the gear box 38 associated with the motor 35 isconnected to drive a disk 6t) mounted concentrically with, butindependently of,

the cam shaft '37. The disk 60' rotates the camshaft 37, and thus thecams 36, 45, by means of a pin 61 extending parallel to the camshaft 37through a hole 62 formed in the cam 36. It can be seen that when the pinis disposed at one edge of the hole 62, the motor 35 must rotate thedisk 60 through a distance approximately equal to the diameter of thehole 62 so that the pin 61 may engage the opposite side of the hole andimpart a rotational force to the cam 36.

To insure that the disk 60 and the motor 35 are properly backed off sothat the pin 61 is adjacent the proper edge of the hole 62, a torsionspring 63 is fixed to the camshaft 37 and is tensioned to exert aresilient force against the pin 61 in a direction opposite to thatimparted by the motor 35. It can thus be seen that momentaryenergization of the motor 35, caused by briefly closing the contacts 67as a result of spurious, transient signals being picked up by thecarrier signal receiver R, will only cause the disk 66 to beginrevolving and start to carry the pin 61 across the hole 62. Upon thealmost immediate deenergization of the motor 35 the torsion spring 63will return the pin 61, disk 60 and the gear train in gear box 38 backto their original starting positions. It will be apparent then that theoperating cycle of cams 36, 45 can be initiated only by energizing themotor 35 for a sustained, predetermined period, which will be the casewhen a signal of several seconds duration is transmitted by the masterclock to be received by the carrier signal receiver R. V

To hold the camshaft 37 and the cams 36, 45 in their starting positionsagainst the reaction force exerted by the torsion spring 63, theinherent detenting effect exerted by the switch actuator for switch 25is utilized. As can be seen in FIG. 2, the switch 25 is provided with aresilient actuator having a detent portion 56 which drops into thenotch-like interruption in the dwell portion 41 of the cam 36. It willbe understood that the engagement of the switch actuator 55 with thenotch-like portion of the cam 36 will hold the cam 36, the camshaft 37,and the cam 45 in their respective starting positions with a detentaction. When the motor 35 remains energized for a time sufiicient tobring the pin 61 into engagement with the opposite side of the hole 62,the cam 36 will be rotated so as to bring the detent portion 56 of theswitch actuator 55 up onto the dwell portion 41 of the cam so that theswitch 25 is operated and the correcting cycle initiated.

In order to minimize the resilient force required to be exerted by thetorsion spring 63 while insuring that the force is suflicient to backoff the disk 61 and the gear train in the gear box 38, the motor 35preferably includes an automatically operating clutch of a type which iscommonly employed for such purposes. In clutch motors of this type, themotor armature is automatically engaged with the power output drivingtrain upon energization of the motor winding, and is disengaged upon thedeenergization of the motor winding. An example of a motor of this typehaving such an automatically operating clutch construction can be seenby reference to U.S. Patent No. 2,334,040, issued November 9, 1943. Itwill be sufficient for present purposes to observe that the armature inthe motor 35 is connected to the driving train in the gear box 38 onlywhen the motor is energized. When the motor is only briefly energizedthrough the action of a spurious signal causing the contacts 37 toflutter momentarily, the gear train in the gear box 38 and the disk arebriefly advanced by the motor armature and then completely disconnectedfrom the armature. Thus, the torsion spring 63 need rotate only the disk60 and the gears within the gear box 38 back to their initial startingpositions, and is not required to rotate the entire armature of themotor 35.

It can be seen that the adaptor 10 may be compactly constructed, sinceit comprises only two small synchronous motors, each of which operatesbut two switches.

lso it can be seen that the components comprising the actuator 10 areconventional in nature, and therefore readily and economicallyavailable. Moreover, the adaptor 10 is completely reliable in operationsince the time delay device 4i) prevents inadvertent actuations of theadaptor in response to spurious, transient or stray signals in the A.-C.power system. It will be understood that the delay device 40 willcontinue to return the driving train extending from the motor 35 to itsinitial starting position after each spurious signal, even though asuccessive series of transient signals causes repeated intermittentoperations of the relay 66.

Resume of operation Briefly recounting the normal sequence of switchoperation when the adaptor it) is used in a typical installation, itwill be recalled that the motor remains continuously energized, by meansof a circuit through the contacts 21, for fifty-nine consecutiveminutes. Each minute the motor 26 drives the camshaft 28 through onerevolution, and therefore, once a minute, the cam 26 closes the contacts30, energizing the solenoid 12 and thus advancing in one minuteincrement, the step-by-step timing mechanism 11.

At exactly fifty-nine minutes past the hour, the master clock M causesthe carrier signal transmitter T to impose a suitable signal on theA.-C. lines to which the terminals 13, 14 are connectech The carriersignal receiver R responds to the signal and energizes the relay 66,which closes the contacts 67 and energizes the motor 35. Energization ofthe motor 35 causes rotation of the carnshaft 37, after a suitable timedelay imposed by the time delay mechanism 40, and operates the switch25. Operation of the seal-in switch opens the contacts 21, thusinterrupting the normal circuit energizing the motor 20, and closes thecontacts 42, thus maintaining energization of the motor 35. Operation ofthe switch 25' also opens the contacts 31, 32 and closes the contacts43, 44, which has the effect of reversing the polarity of the D.-'C.current obtm'nable from the rectifier 17. As the motor rotates thecamshaft 37, the cam intermittently closes the contacts 47 to complete acircuit transmitting rapid, DC, current impulses of reverse polarity tothe solenoid 12 which causes the associated tautoset mechanism tocorrect, if necessary, the reading of the timing device 11 by bringingthat reading to fiftynine minutes past the hour.

As the motor 35 is operating, the cam St) on the camshaft 28 will holdthe contacts 52 closed and thereby maintain energization of the motor 20until the cam 50 allows the contacts 52 to open. The cam 50 ispositioned to interrupt the operation of the motor 20 in a positionwhere the dwell portion 29 of the cam 26 is poised to immediately closethe contacts 30 when the mot-or 20 is reenergized.

After the camshaft 37, driven by the motor 35, completes a singlerevolution during the interval from fiftynine minutes to sixty minutespast the hour, the seal-in cam as releases the seal-in switch 25 so thatthe contacts 42 open, deenergizing the motor 35, and the contacts 21close, reenergizing the motor 20. At the same time, the contacts 43, 44are opened and the contacts 3-1, 32 are again closed, so that as themotor 26 begins normal rotation of the camshaft 28, the cam 26 willclose the contacts 30 and a current impulse of normal polarity will betransmitted to the timing device 11.

Since the motor 35 begins operating at fifty-nine minutes past the hourand since its cycle of operation is ex-= actly one minute, thereenergization of the motor 26 and immediate closing of the contacts 3t}will advance the timing device 11 from a position indicating fifty-nineminutes past the hour to a position indicating the new hour in almostexact synchronism -with the master,

clock M.

I claim as my invention:

1. An adaptor for operating a D.-C. timing device on an A.-C. system andcapable of producing regularly intermittent D.-C. impulses of desiredpolarity and a rapid predetermined series of ll-C. impulses of reversepolarity comprising, in combination, a rectifier connected to said A.-C.system to provide a source of D.-C. current, a first synchronous motorenergized from said A.-C. system, means including a cam controlledswitch operated by said motor for normally transmitting from said D.-C.source a regularly intermittent series of current impulses of desiredpolarity, a second synchronous motor energized from said A.-C. system,means responsive to a carrier signal on said A.-C. system to initiateenergization of said second motor, means including a cam controlledswitch for maintaining energization of said second motor through apredetermined time interval, means including cam controlled switchesoperated by said second motor when energized for interrupting operationof said first motor and reversing the polarity of said D.C. source, andmeans including a cam controlled switch operated by said second motorwhen energized for transmitting from said D.-'C. source a rapid seriesof current impulses of reverse polarity.

2. An adaptor for operating a D.-C. timing device on an A.-C. system andcapable of producing regularly intermittent D.-C. impulses of desiredpolarity and a rapid predetermined series of ll-C. impulses of reversepolarity comprising, in combination, a rectifier connected to said A.-C.system to provide a source of D.-C. current, a first synchronous motorenergized from said A.-C. system, means including a cam controlledswitch operated by said motor for normally transmitting from said D.-C.source a regularly intermittent series of current impulses of desiredpolarity, a second synchronous motor energized from said A.-C. system,means responsive to a carrier signal on said A.-C. system to initiateenergization of said second motor, means including a cam controlledswitch for maintaining energization of said second motor through apredetermined time interval, means including cam controlled switchesoperated by said second motor when energized for interrupting operationof said first motor and reversing the polarity of said DC. source, meansincluding a cam controlled switch operated by said second motor whenenergized for transmitting from said D.-C. source a rapid series ofcurrent impulses of reverse polarity, and a spring biased lost-motionconnection between said second motor and its said cam controlledswitches arranged so that the motor must overcome the spring force andtake up the lost motion before operating said switches in order thatspurious, transient signals will not unintentionally operate theswitches.

3. In an adaptor for operating a D.-C. timing device on an A.-C. systemand capable of producing regularly intermittent D.-C. impulses ofdesired polarity and a rapid predetermined series of D.-C. impulses ofreverse polarity, the combination comprising, means for normallygenerating for said D.-C. timing device a regularly intermittent seriesof RC. current impulses of desired polarity, a motor and means driven bysaid motor for interrupting said intermittent series and generating forsaid D.-C. timing device a rapid series of D.-C. current impulses ofreverse polarity, means responsive to a remotely generated signal at apredetermined time for energizing said motor, and a spring-biased, lostmotion connection between said motor and said driven means arranged sothat the motor must overcome the spring force and take up the lostmotion before operating said means in order that transient, spurioussignals will not unintentionally operate said driven means.

4. An adaptor for operating a D.-C. timing device on an A.-C. system andcapable of producing regularly intermittent D.-C. impulses of desiredpolarity and a rapid predetermined series of D.-C. impulses of reversepolarity, comprising, in combination, a source of D.-C. current, a firstsynchronous motor energized from said A.-C. system, means operated bysaid first motor for transmitting from said D.-C. source, successivecurrent impulses of desired polarity, each impulse being sent at a fixedpredetermined time interval, a second synchronous motor energized fromsaid A.-C. system, means responsive to a carrier signal on said A.-C.system for energizing said second motor and maintaining saidenergization through a period at least equal to said time interval,means operated by said second motor when energized for interruptingoperation of' said first motor and for reversing the polarity of saidDHC. source, means operated by said first motor for insuring that, whenoperation of that motor is interrupted, it will stop only in a positionwhere the motor immediately upon energization operates said means fortransmitting successive impulses of desired polarity, and means operatedby said second motor when energized for transmitting from said D.-C.source a rapid series of current impulses of reverse polarity.

5. An adaptor for operating a direct current slave I clock having anautoset mechanism on an alternating current power line comprising, incombination, a first synehronous motor energized from said power line, acam operated time switch driven by said first motor, a source of directcurrent, said time switch connected in circuit with said autosetmechanism and said source of direct current, said time switch beingclosed at regularly spaced preselected time intervals by said firstmotor to provide said autoset mechanism with timed driving pulses ofpositive relative polarity, a second motor, relay means responsive to acorrection signal from a remote master clock at preselected times tomomentarily connect said second motor to said power line forenergization thereof, seal-in switch means responsive to energization ofsaid second motor for connecting said second motor to said power linefor a preselected correction interval, a cam operated correction switchdriven by said second motor, said seal-in switch means also connectingsaid correction switch in circuit with said autoset mechanism and saidsource of direct current, said correction switch being closed by saidsecond motor a plurality of times at a more rapid rate than said timeswitch to provide said autoset mechanism with a rapid series ofcorrecting pulses of negative relative polarity. v

6. The combination of claim and time delay means responsive toenergization of said second motor and 10 responsive to energization ofsaid second motor and adapted to delay the response of said seal-inswitch means for a predetermined interval, whereby said seal-in switchmeans is unresponsive to spurious signals received by said relay means.

' 12. The combination of claim 11 wherein said relay means is connectedto said alternating current power line and is responsive to a modulatedcorrection signal transmitted over said power line.

13. An adaptor for operating a direct current secondary clock having anautoset mechanism on an alternating current power line comprising, incombination, a synchronous minute impulse motor normally energized fromsaid power line, a minute impulse cam driven by said minute impulsemotor, a minute impulse switch operated by said minute impulse cam, asource of direct current,

. said minute impulse switch connected in circuit with said adapted todelay the response of saidseal-in switch means for a predeterminedinterval, whereby said seal-in switch means is unresponsive to spurioussignals received by said relay means. i

7. The combination of claim ,5 wherein said relay means is connected tosaid alternating current power line and responsive to a modulatedcorrection signal transmitted over said power line.

8. The combination of claim 5 wherein said seal-in switch meansdisconnects said first motor from said power line when said second motoris energized.

9. The combination of claim 8 and an 'ofi normal cam switch driven bysaid first motor, said ofif normal switch connecting said first motor incircuit with said power line until a predetermined time prior to closureof said time switch, whereby when said first motor is disconnected fromsaid power line by said seal-in switch means said first motor remainsenergized'through said off normal switch until said predetermined time.

10. The combination of claim 9 wherein said relay means is connected tosaid alternating current power line and is responsive to a modulatedcorrection signal transmitted over said power line.

11. The combination of claim 9 and time delay means tion of said seal-inswitch by said seal-in cam unless said autoset mechanism and said sourceof direct current, said minute impulse switch being closed at minuteintervals by said minute impulse cam to provide said autoset mechanismwith minute driving pulses of positive relative polarity, a synchronouscorrection motor, a relay responsive to an hourly correction signal froma remote master clock to momentarily connect said correction motor tosaid power line for energization thereof, a sealin cam driven by saidcorrection motor, a seal-in switch operated by said seal-in cam adaptedto connect said correction motor to said alternating current power lineindependently of said relay for a preselected correction interval, saidseal-in switch also adapted to disconnect said minute impulse motor fromsaid alternating current supply line, a correction cam driven by saidcorrection motor, a correction switch operated by said correction cam,said seal-in switch adapted toconnect said correction switch in circuitwith said autoset mechanism and said source of direct current, aplurality of teeth on said correction cam adapted to open andclose saidcorrection switch rapidly during said preselected interval to providesaid autoset mechanism with a rapid series of correcting pulses ofnegative relative polarity, an off normal cam driven by said minuteimpulse motor, and an olf normal switch operated by I said off normalcam adapted to connect said minute impulse motor to said alternatingcurrent supply line independently of said sealin switch, said ofi normalswitch being closed by said oir 7 biased time delay means interposedbetween said correction motor and said seal-in cam adapted to preventopera- References Cited in thefile of this patent UNITED STATES PATENTSBryce Oct. 16, 1928 1,957,543 Kenerson ...L May 8, 1934 2,332,827 Menardet al. Oct. 26, 1943 2,332,828 Lorenz et al. Oct. 26, 1943 2,662,367

Riggs Dec. 15, 1953

